TDA8933B Datasheet, PDF (7/42 Pages) NXP Semiconductors – Class D audio amplifier

NXP Semiconductors
TDA8933B
Class D audio amplifier
V_P
POWERUP
DREF
OSCIO
HVPREF
HVP1, HVP2
2.0 V (typical)
ENGAGE ^{1.2 V (typical)}
OUT1, OUT2
AUDIO
PWM
DIAG
PWM
AUDIO
AUDIO
PWM
≤ 0.8 V
Fig 3. Start-up sequence
operating
mute
operating fault
operating
sleep
010aaa457
8.3 Pulse Width Modulation (PWM) frequency
The output signal of the amplifier is a PWM signal with a carrier frequency of
approximately 320 kHz. Using a 2^nd-order low-pass filter in the application results in an
analog audio signal across the loudspeaker. The PWM switching frequency can be set by
an external resistor R_osc connected between pin OSCREF and V_SSD(HW). The carrier
frequency can be set between 300 kHz and 500 kHz. Using an external resistor of 39 kΩ,
the carrier frequency is set to a typical value of 320 kHz (see Figure 4).
If two or more TDA8933B devices are used in the same audio application, it is
recommended to synchronize the switching frequency of all devices. See Section 14.6 for
more information.
The value of the resistor also sets the frequency of the carrier and can be calculated with
Equation 1:
f _osc
=
1_---2_---._--4_---5_---x_----1_---0_---⁹
R_osc
(1)
Where:
f_osc = oscillator frequency (Hz)
TDA8933B_1
Preliminary data sheet
Rev. 01 — 23 October 2008
© NXP B.V. 2008. All rights reserved.
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